Multiple stage refrigeration



' 1948- B. s. WILLIAMS 2,

MULTIPLE STAGE REFRIGERATION Filed llarclr 21, 1946 HIGH mmvrom BURDELL S. M/lLL/AM 5 Pawnee Nov. 16,1948 r "x 2,453,823-

'UNlTED STATES PATENT orri'ca M MULTIPLE STAGE REFRIGERATION Burdell S. Williams, Oakwood, Ohio, assignor -to Chrysler Corporation, Highland Park, Mich, a corporation of Delaware Application March 21, 1946, serial No. 656,009 1 2 Claims. "(CL 62-115) My present invention relates to cascade refrig- 1941, and a condenser such as disclosed in the eration and has for its principal object to achieve patent to Jewell, No. 2,149,737 of March 7, 1939. abnormally low temperatures, such as in com- Other types of compressors and condensers may. partments where articles may be tested at arctic be used without departing from the spirit of my or sub-arctic temperatures. The invention has 5 invention. I particular utility in connection with the testing A body of refrigerant is compressed and conof parts for use in airplanes intended to operate densed by the condensing unit ill, the compressed in the stratosphere, but many other utilites will refrigerant being discharged into the shell of a be apparent to manufacturers or users of manucondenser it through which passes a tube carrytactured goods. A further purpose for which the ing water from a source of supply under control invention is applicable is in the quick freezing of of a valve 5. The water, after cooling the refood stuffs. The ultimate uses of the invention .frigerant, passes through a compressor lubricant are wide and varied and form no limitation of the cooling coil M in the high stage compressor, then through a compressor lubricant cooling coil It in scope of my invention.

A further object of my invention is to provide the intermediate stage compressor, and is then low temperature refrigeration by the use of a discharged to adrain or'thelike. Asuitable form plurality of condensing units of the compressorof compressor cooling coil is disclosed in the condenser type, connected in series whereby a patent to Simons, No. 2,192,654 of March 5, 1940. high stage condensing unit employing a first The liquid refrigerant condensed in shell i3 passes separate volume of volatile refrigerant is used to through a hand valve l6, strainer l1, expansion condense a second separate volume of refrigerant valve it under control of a superheat bulb 2 reture of the suction to the in an intermediate stage condensing unit, which fleeting the tempera in turn is used to condense a third separate volhigh stage compressor, coils in series in the conume of refrigerant in a low stage condensing unit, denser shell til of the intermediate stage condensf refrigerant is used to per- 95 ing unit ll, compressor cooling coil 2i in the low which third volume 0 stage compressor, and back to the suction inlet form the actual work of refrigeration. By the use of my system I avoid complicated and exof the high stage compressor. Thus, the body of pensive multiple stage compressors or condensers. refrigerant employed in the first condensin unit A further object of my invention is th so1uis expanded to cool the refrigerant in the second tion of the problem of achieving low temperacondensing unit and the compressor of the third ture by the use of ordinary refrigerants in an condensing unit. economical and emcient manner. It is well Gas which is Compressed by the t r ediate known that certain refrigerants provide economistage comp iS c n nsed in the shell '20 cal operation when condensed at normal temperaa d p s s ou a hand Valve S r tures such as provided by average city water, expansion valve 2t controlled by a superheat whereas the same refrigerant would be very unblllb 29 on the suction inlet to the intermediate economical or impractical at lower temperatures. stage p r. coils in s s n t nd ns r- By cooling one body of volatile refrigerant of one Shell w of t e low stage condensin t a d type by t use of city water and employing t back to the intermediate stage compressor. A refrigerantto cool asecond bodyof asecond type rate body of refrigerant is thus passed of refrigerant I am able to achieve abnormally ugh a refrigeration cy e to 0001 he conlow temperatures in a highly eficient manner. denser Of the low Stage clmdensing unit- These and other objects and advantages of my Gas which is compressed in the compressor of invention will be apparent from" the following the low stage condensing unit it is cooled and specification taken in connection with the acw liqu fied in the shell it and passes throu h hand companying drawing. valve hi to a discharge pipe 3?. Pipe 32 has a In the drawings the figure is a schematic repbranch containing the usual expansion valve 33 resentation of the refrigeration system. which permits variable amounts of refrigerant Referring to the figure there is disclosed a high to pass to liquid pipes 3t and 35 inparallei. Pipe stage condensing unit iii, an intermediate stage 36 leads to expansion coils t6 and 31 in series and condensing unit ii and a low stage condensing pipe 35 leads to expansion coils 38 and 39 in unit it. Each of these units comprises an e1ecseries. The coils 36, 31, 38 and 39 may be artri al y dnv hermetically a d mpressor, a ranged. against the four walls, respectively 40, 4| suitable form of which is illustrated and claimed 42 and 63, of a first cooling compartment, bu in the patent to Neeson, No. 2,247,449 of July 1, 3 may obviously be arranged in desired manne branch pipes 3 in separate compartments, or together or otherwise separated for various purposes. Coils 36 and 31 lead to branch suction pipe 44, and/coils 38 and 39 lead to branch suction pipe 46, which are joined to suction pipe 46 having a manual valve ll therein and which leads to a tank 48 from which the suction pipe of the low stage compressor extends. The tank 66 provides means to insure against passage of liquid into the compressing unit. A superheat bulb 50 is attached to the pipe 46 at the outlet side of valve 41 and is connected to the expansion valve 33 to regulate the volume of refrigerant passed therethrough in accordance with known principles.

Liquid pipe 32 contains an expansion valve '5! feeding controlled amounts of refrigerant to 52 and 53. Ripe 52 leads to expansion coils 54 and 55 in series, and pipe 53 leads to expansion coils 58 and 51 in series. Coils 54, 55, 56 and 51 may be arranged along the walls 58, 59, 60 and 6| of a second cooling compartment or otherwise arranged as described with the first set of expansion coils. Coils 53 and 51 are connected to pipe 62, and coils 54 and 55 to pipe 63, which are joined to branch suction pipe 64. The pipe 64 has therein a manually set valve 65 and returns to the tank 48 from which the expanded gas re-enters the low stage compressor. A superheat bulb 66 attached to pipe 64 controls valve I -in accordance with known principles.

The'cooling effect in each compartment will be under control of the setting of valves 41 and 65 which may be balanced one against the other to permit lesser flow of refrigerant to one than to the other, or all to one and none to the other,

'or equal flow if equal temperatures in the two compartments are desired. As permitted by the extent of opening of valves 41 or 65, the expansion valves 33 and 5| will regulate the flow to the expansion coils in accordance with the superheat setting of the valves.

It is to be appreciated that the high stage condensing unit may comprise an air cooled condenser or other suitable form of condensing means but I prefer a water cooled condenser for economy and simplicity. I prefer using dichlorodifluoromethane for the high stage refrigerating medium, dichlorodifluoromethane for the intermediate stage refrigerating medium and monochlorodifluoromethane for the low stage refrigerating medium. By the use of such refrigerants I am able to obtain economy of operation and high eiiiciency since each body of refrigerant is em ployed at temperatures and pressures for which it is most suited.

Having illustrated and described a preferred embodiment of my invention, I nevertheless claim all such modifications thereof as come within the scope of the following claims:

1. The method of achieving abnormally low temperatures through the use of a. plurality of mechanical condensing units requiring lubrication, comprising passing a gaseous refrigerant through a high stage cycle, employing water to condense the high stage refrigerant and to cool the lubricant of at least one condensing unit, employing the high stage refrigerant to condense the refrigerant of a succeeding condensing unit and to cool the lubricant of a final low stage condensing unit, passing a second volume of gaseous refrigerant through an intermediate refrigeration cycle, employing the intermediate cycle refrigerant to condense the refrigerant of the low stage condensing unit, and employing a third volume of gaseous refrigerant in the final lowstage refrigeration cycle.

2. A cascade refrigerating system comprising a high stage condensing unit including a high stage compressor and a high stage condenser, an intermediate stage condensing unit including an intermediate stage compressor, and an intermediate stage condenser, a low stage condensing unit including a low stage compressor and a low stage condenser, a water circulating system'including a portion for cooling said high stage condenser and other portions for cooling said high stage and said intermediate stage compressors, a first refrigerant circulating system including said high stage condensing unit and comprising an expander for cooling said intermediate stage condenser and an extension thereof for cooling said low stage compressor, a second refrigerant circulating system including said intermediate stage condensing unit and comprising an expander for cooling said low 'stage condenser, and a third refrigerant circulating system including said low stage condensing unit and comprising expansion means for extracting heat from a space to be cooled.

BURDELL S. WILLIAMS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

